#ifndef STIM_CUDA_MAG3_H
#define STIM_CUDA_MAG3_H

#include <iostream>
#include <cuda.h>
#include <stim/cuda/cudatools.h>
//#include <stim/cuda/sharedmem.cuh>
#include <stim/cuda/cudatools/error.h>

		template<typename T>
		__global__ void mag3(T* out, T* in, int x, int y, int z){

			
			//calculate x,y,z coordinates for this thread
			int xi = blockIdx.x * blockDim.x + threadIdx.x;
			//find the grid size along y
			int grid_y = y / blockDim.y;
			int blockidx_y = blockIdx.y % grid_y;
			int yi = blockidx_y * blockDim.y + threadIdx.y;
			int zi = blockIdx.y / grid_y;
			int i = zi * x * y + yi * x + xi;

			if(xi >= x|| yi >= y || zi>= z) return;

			float xl = in[i * 3 + 0];
			float yl = in[i * 3 + 1];
			float zl = in[i * 3 + 2];
				
			out[i] = sqrt(xl * xl + yl * yl + zl * zl);
							
		}


		template<typename T>
		void gpu_mag3(T* gpu_mag, T* gpu_cart, unsigned int x, unsigned int y, unsigned int z){

			
			int max_threads = stim::maxThreadsPerBlock();
			dim3 threads(sqrt (max_threads),sqrt (max_threads));
			dim3 blocks(x / threads.x + 1, (y / threads.y + 1) * z);

			//call the GPU kernel to determine the gradient
			mag3<T> <<< blocks, threads >>>(gpu_mag, gpu_cart, x, y, z);

		}


		template<typename T>
		void cpu_mag3(T* out, T* in, unsigned int x, unsigned int y, unsigned int z){

			//calculate the number of bytes in the array
			unsigned int bytes = x* y* z * sizeof(T);

			//allocate memory on the GPU for the input data.
			T* gpu_cart;
			cudaMalloc(&gpu_cart, bytes*3);
			cudaMemcpy(gpu_cart, in, bytes*3, cudaMemcpyHostToDevice);
			
			//allocate memory on the GPU for the magnitude
			T* gpu_mag;
			cudaMalloc(&gpu_mag, bytes);

			//call the GPU version of this function
			gpu_mag3<T>(gpu_mag, gpu_cart, x, y, z);

			//copy the array back to the CPU
			cudaMemcpy(out, gpu_mag, bytes, cudaMemcpyDeviceToHost);

			//free allocated memory
			cudaFree(gpu_cart);
			cudaFree(gpu_mag);

		}


#endif